Throw exception on disposed. We should always throw this one as it is pretty fatal so you would not want this to silently show up in the Exception response value. (#1967)

Author: kendallb

src/RestSharp/RestClient.Async.cs

@@ -49,6 +49,11 @@ public async Task<RestResponse> ExecuteAsync(RestRequest request, CancellationTo
     async Task<InternalResponse> ExecuteInternal(RestRequest request, CancellationToken cancellationToken) {
         Ensure.NotNull(request, nameof(request));
 
+        // Make sure we are not disposed of when someone tries to call us!
+        if (_disposed) {
+            throw new ObjectDisposedException(nameof(RestClient));
+        }
+
         using var requestContent = new RequestContent(this, request);
 
         if (Authenticator != null) await Authenticator.Authenticate(this, request).ConfigureAwait(false);